The present invention relates generally to the field of filters and more particularly to an automated filter changing device and method.
Filters are used to remove particles from the air used for heating or cooling enclosures. Fans commonly pull the air through these filters. As the filters get dirty the air flow is reduced. Eventually the air flow is so low that the device cannot heat or cool the enclosure efficiently. At this point or sooner the filter needs to be replaced. In some cases these enclosures are not easy to access. For instance, variable message highway signs require cooling and are often hard to access. Changing the filters in these signs requires a maintenance person to drive miles and climb into the sign to change the filter. Commonly, the maintenance people set up a standard schedule to change these filters. This results in the filters being changed unnecessarily or not being changed soon enough. As a result this process is very expensive and inefficient.
Prior art systems have measured the pressure of the air on the filter to determine when a filter requires changing. Unfortunately, these pressure sensors do not give an indication of the airflow. The pressure may not be above a threshold because the fan is not working or there is a hole in an associated plenum. As a result, there is inadequate airflow but the pressure sensor does not sense these problems.
Thus there exists a need for an automated filter changing device that overcomes these and other problems.